Simultaneous Observation of Near-Inertial Frequency Gravity Waves by a Long-Duration Balloon and the PANSY Radar in the Antarctic

Abstract

Simultaneous observations using a long-duration balloon and the PANSY radar, a large-scale atmospheric radar, were performed at Syowa Station in the Antarctic, from January to February 2022. They captured near-inertial frequency gravity waves (NIGWs) in the lower stratosphere. The analysis using both datasets and the latest reanalysis ERA5 revealed that two NIGW packets with an upward group velocity and short vertical wavelengths of less than 3 km propagated northeastward and eastward above Syowa Station. Although the NIGWs over Syowa Station were qualitatively represented by ERA5, their amplitudes were underestimated. In addition, the latter NIGW packet was observed by the long-duration balloon, but not represented by ERA5. It could be because the vertical wavelength of NIGW became shorter than the lower limit of vertical wavelength explicitly represented in ERA5 by entering the high static stability region around the balloon, or due to explicit and implicit diffusion and/or misrepresentation of the position of the NIGW packet in the model. This result implies the difficulty to explicitly represent the behavior of NIGWs with short vertical wavelengths even in the high-resolution simulation.